Marine fenders are designed to protect boats, piers, pontoons etc. from any damage caused by impact or rubbing between them. Whilst a series of discrete rigid plastic air-filled fenders are sometimes used, extended pontoons etc. are usually continuously `lined` with an elongate elastic strip, and the most widely used material for this is natural or synthetic rubber. However, rubber strips are not only considered `unsightly` (possibly especially to leisure boat owners), but they can also mark a boat hull even upon light impact. Such marks can again be unsightly, as well as being difficult and expensive to remove. Actual damage to the boat is even possible on heavy impact. Much of this is because the rubber material of such strips is relatively hard and has low compressibility.